Air brush



R. W. TRACY Dec. 23, 1930.

AIR BRUSH Filed Jan. 10, 1929 Patented Dec. 23, 1930 UNITED STATESPATENT OFFICE ROBERT W. TRACY, OF TOLEDO, OHIO, ASSIGNOR TO THE DEVILBISS COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO AIR 3111151:

Application filed January 10, 1929. Serial in. 331,570.

This invention relates to a spraying de vice of the type commonly knownas an air brush, and it is constructed with special reference to its usein the art of spray painting.

In spray painting, as the fluid paint leaves the nozzle, there is alwaysa tendency for it to spread or scatter in all directions from the centerline of the stream and it is therefore desirable to provide means toflatten the stream so that it may be caused to assume the shape of a fanand so that the paint, as it reaches the object to be painted, will beapplied thereto in the form of a thin, flat, uniform sheet. Variousdevices have heretofore been proposed for flattening the paint stream bymeans of supplemental air jets directed against the sides thereof, butthe operation of such devices has been more or less imperfeet because ofthe great difficulty in maintaining precisely the correct pressure onthe supplemental jets or in producing jets of the proper shape anddirection to flatten the stream into a sufficiently thin sheet withoutsplitting the same or at least making'some portions thereof thinner thanother portions.

It is with the above conditions in mind and with the object ofovercoming the difliculties mentioned, that the present invention hasbeen perfected.

The specificconstruct-ion of the invention in its. present form and theprinciples of its operation will be explained particularly in connectionwith the accompanying drawing, the single figure of which represents acentral longitudinal section through. the discharge end of the sprayhead.

In the spray head in connection with which the invention isillustrated,the body portion 1 is provided with a central passageway 2 through whichthe paint-passes. liquid nozzle 3 is secured to the body portion at theoutlet end of the passageway 2 by means of a union 4. This nozzle 3 hasa tapered outlet 5 through which the flow is controlled by means of aneedle valve 6.

An'air nozzle 7 encompasses the liquid nozzle 3 and is secured to thebody 1 by means of a union 8. This air nozzle is so designed as to leavean air chamber 9 surrounding the liquid nozzle 3 and air under pressureis supplied through a passageway 10 in the body 1.

from the chamber 9 and each of these passages has two outlets 13 and 14.These outlets 13 and 14 converge toward their mouths and both inclinetoward the paint laden stream, so that the air streams emitted from theoutlets 1'3 and 14, as shown by the dot and dash lines, merge togetherbefore they strike the paintladen stream and are both. flattened out toform a single fan-shaped supplemental jet oneach side of the mainstream.In this manner the effect of each supplemental jet is softened so thatit will not penetrate or scatter the aint stream, and a further eflectof the con uence of the two air streams emitted from the outlets 13 and14 is to spreadthe jets around the paint stream so that they sub:stantially envelop the same and at the same time flatten it into theshape of a comparatively thin fan of uniform thickness.

While I have shown and described the invention in connection with onespecific type of spray head, it is obvious that the invention is notlimited thereto, but may be used in connection with an spray head usingcompressed air'or a similar medium for effecting the discharge. of thematerial stream. It is to be understood, therefore, that the inventionincludes all such modifications as fall within the scopeof the appendedclaims.

What I claim is:

1. An air brush provided with means for discharging a material ladenstream by the use of air under pressure, and meansfor dischargingsupplemental air jets against oppo- 2. In an air brush, means fordischarging a material laden stream by the use of air under pressure,and means for discharging supplemental air jets against opposite sidesof the main stream to flatten the same, said last means including a setof at least two air discharge orifices at each of opposite sides of themain stream with the lines of discharge of the outer orifices of the twosets converging and intersecting at a point on the axis of the mainstream and with the lines of discharge of the next orifice of each setntersecting the line of discharge of the outer orifice of the respectiveset at a point spaced from but adjacent to the main stream whereby thesupplemental air streams of each set merge and form fan-like air streamsbefore striking the main stream.

In testimony whereof I have hereunto signed my name to thisspecification.

ROBERT W. TRACY.

